Phillips joined CNN in 1999.[5] During her early years at CNN, Phillips was granted access to U.S. Navy Air Wing CVW-9 in 2001 as they prepared for the war in Afghanistan. In January 2002, Phillips spent about a month in Antarctica to work on a television documentary to be featured on the program CNN Presents. Later in 2002, Phillips produced reports focusing on the U.S. Navy’s reconnaissance missions from the USS Paul Hamilton, the Navy’s Special Operations Command, the Navy SEALs, and Special Warfare Combatant Crewman training, riding in an F-14 Tomcat during an air-to-air combat mission over the Persian Gulf. She has also participated in the Navy’s TOPGUN school, SWAT training, and other police and weapons training.

In March 2012, Phillips moved to the 11am Newsroom, and her timeslot was shortened to one hour.[7] However, on 26 June 2012, it was officially announced that she would leave CNN and launch her own show at its sister channel HLN.[8] She soon returned to CNN as a "investigative correspondent". On April 2, 2018, Phillips left CNN to join ABC News as a "D.C.-based correspondent".[9]

On July 19, 2019, Phillips
posted a tweet praising President Trump for giving us (journalists) access "on a regular basis and the ability to ask any question". Phillips came under attack by many who viewed the comment as being a "suck up" to the president.

In 1997 Phillips was named Reporter of the Year by the Associated Press.[4] She has also won four Emmy Awards, two Edward R. Murrow Awards for investigative reporting,[4] the top documentary award from the Society of Professional Journalists for her coverage of Jena, Louisiana and multiple Golden Microphones.